Answer:
The total cost is $41.
Explanation:
The given expression is :

Now we know that the roses are represented by = r
And the petunias are represented by = p
So, we can say that each rose costs $3 (3r) and each petunia cost $2.5 (2.5p)
So, we can now find the total value of 7 roses and 8 petunias.
Cost of 1 rose = $3
Cost of 7 roses is =

Cost of 1 petunia is = $2.5
Cost of 8 petunias is =

Total cost of the flowers =
= $41.